Ion implanter

ABSTRACT

An ion implanter having means for scanning an ion beam on a wafer is provided, wherein the scanning means, on which the wafer is mounted, moves the wafer in a region where the ion beam is irradiated. A detecting means, which is fixedly mounted adjacent to the scanning means, detects the ion beam that is overly scanned out of the scanning means. The detecting means has an inclined surface so that a portion of the detecting means adjacent to the scanning means is positioned below a surface of the wafer that is disposed on the scanning means. Accordingly, the ion implanter may prevent the wafer in the scanning means from being polluted with sputtering particles generated from a surface of the scanning means.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an ion implanter. Moreparticularly, the present invention relates to an ion implanter capableof effectively reducing sputtering particles therein.

[0003] 2. Description of the Related Art

[0004] Recently, 256 Megabyte DRAM cells have been fabricated by aprocess satisfying a design rule provided that a width between circuitlines is less than 0.18 μm. However, when the 0.18 μm design rule isapplied in the fabrication process, particles, which are generated in aprocess chamber, have a tendency to cause defects in semiconductordevices, thereby decreasing a yield of products. Particularly, when 1Gigabyte DRAM cells or 4 Gigabyte DRAM cells, conventionally known asthe next generation memory devices, are developed, the particlesgenerated in the process chamber during fabrication of the devices causevarious technical difficulties and fabrication limitations. Hence, theparticles are generally recognized as a barrier to be overcome indeveloping the next generation memory device.

[0005] Accordingly, semiconductor device manufacturers have made a greateffort and invested significant amounts of time to determine causes ofthe particles and methods of managing the particles in order to reducetheir numbers and to prevent wafer pollution due to the particles in thefabrication of the semiconductor device.

[0006] In particular, wafer pollution caused by the particles has aparticularly substantial effect on electrical characteristics of asemiconductor device when the particles are generated in an ionimplanting process.

[0007] According to a conventional ion implanting process, acceleratedions are impacted to the wafer disposed in an ion implanter and then apredetermined amount of ions are implanted to a surface of the wafer ata predetermined depth.

[0008] The particles generated in the ion implanter are generallydivided into two categories: mechanical particles and electricalparticles. Most of the electrical particles are sputtering particlesgenerated by high-speed impact of the ions to a metal surface andactivation by an electrostatic force of an ion beam. The mechanicalparticles are generated by frictional heat due to motion of a rotationaldevice or a transmission system of the ion implanter.

[0009] In the case of the mechanical particles, a cause of the particlesis easily found and the damage to the wafer is minor. Accordingly, highlevel technology is not required to trace the mechanical particles incomparison with the electrical particles.

[0010] However, in the case of the electrical particles, theelectrostatic force of the ion beam consisting of positive ionsactivates the minute and fine particles and renders the particles to besputtered. Accordingly, the electrical particles cause significantdamage to the wafer and high level technology is required to trace theparticles.

SUMMARY OF THE INVENTION

[0011] The present invention has been made to solve the aforementionedproblem. Accordingly, it is a feature of an embodiment of the presentinvention to provide an ion implanter capable of analyzing a cause ofparticles generated therein and restraining generation of the particlesby changing a structure of elements of the ion implanter, resulting in adecrease of particle-induced damage of wafers processed therein.

[0012] In order to provide these and other features and advantages ofthe present invention, there is provided an ion implanter having meansfor scanning an ion beam on a wafer. The scanning means, on which thewafer is mounted, moves the wafer in a region where the ion beam isirradiated. A detecting means, which is fixedly mounted adjacent to thescanning means, detects the ion beam that is overly scanned out of thescanning means. The detecting means has an inclined surface so that aportion of the detecting means adjacent to the scanning means ispositioned below a surface of the wafer that is disposed on the scanningmeans.

[0013] According to one embodiment of the present invention, aninclination angle of the inclined surface of the detecting means islimited to approximately 10 degrees to 30 degrees. When the inclinationangle is less than 10 degrees, a gradient of the inclined surface is sosmall that the particles are scattered on the wafer, and thus waferpollution is not sufficiently prevented. Similarly, when the inclinationangle is more than 30 degrees, the gradient of the inclined surface isso large that the secondary electrons generated by sputtering cannot becontrolled by means of a faraday cup.

[0014] The scanning means may include either a rotary disc applied in abatch type ion implanter or a wafer holder applied in a single type ionimplanter. The detecting means preferably includes a spillover cup or asampling beam cup that is mounted adjacent to the scanning means todetect the ion beam that is overly scanned out of an edge of thescanning means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other features and advantages of the presentinvention will become readily apparent to those of ordinary skill in theart by reference to the following detailed description when consideredin conjunction with the accompanying drawings in which:

[0016]FIG. 1 illustrates a schematic plan view showing a batch type ionimplanter;

[0017]FIG. 2 illustrates a schematic sectional view showing a sideportion of an end station of the batch type ion implanter shown in FIG.1;

[0018]FIG. 3 illustrates a view explaining a change of particle numbersaccording to a change of a height of a spillover cup from a horizontalsurface of the wafer;

[0019]FIG. 4 illustrates a table of lifetime of the spillover cupcorresponding to a generating current for generating the ion beam;

[0020]FIG. 5 illustrates a graph showing the relationship between acorrosion rate of the spillover cup and the generating current;

[0021]FIG. 6 illustrates a view showing a scattering process ofsputtering particles on a flat surface of the spillover cup of aconventional ion implanter;

[0022]FIG. 7 illustrates a view showing a scattering process ofsputtering particles on an inclined surface of the spillover cup of abatch type ion implanter according to an embodiment of the presentinvention; and

[0023]FIG. 8 illustrates a sectional view showing a sampling beam cup ofa single type ion implanter according to another embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Korean Patent Application No.2001-29914, filed on May 30, 2001,and entitled: “Ion Implanter,” is incorporated by reference herein inits entirety.

[0025] Hereinafter, the present invention will be described in detailwith reference to the accompanying drawings.

[0026]FIG. 1 illustrates a schematic plan view showing a batch type ionimplanter to which the present invention may be applied.

[0027] A batch type ion implanter refers to a multi-type ion implanter,which holds thirteen to twenty-five wafers in one rotary holder incontrast with a single type ion implanter, which holds only one wafer inone wafer holder.

[0028] Referring to FIG. 1, the batch type ion implanter includes aterminal module 100, an end station module 200 and an accelerator 300for connecting the terminal module 100 and the end station module 200.

[0029] The terminal module 100 includes an ion source 110 and a massanalyzer 120. The ion source 110 ionizes a source substance and the massanalyzer 120 separates necessary and unnecessary ions from the ionizedsource substance. The accelerator 300 generates an ion beam byaccelerating the necessary ions separated by the mass analyzer 120 to avoltage of from KeV's to MeV's, and supplies an ion beam 400 to the endstation 200.

[0030] The end station 200 includes a scanning device 220 and awafer-transferring device 230 in a high vacuum chamber 210. Beforeimplanting ions into a wafer W, the wafer-transferring device 230 loadsthe wafer W from a wafer carrier 250 that is placed on a wafer station240, to the scanning device 220. After implanting the ions into thewafer W, the wafer-transferring device 230 unloads the wafer W from thescanning device 220 to the wafer carrier 250. The high vacuum chamber210 is continuously kept in a high vacuum during the implantationprocess.

[0031]FIG. 2 illustrates a schematic sectional view showing a sideportion of the end station module 200 of the batch type ion implantershown in FIG. 1.

[0032] Referring to FIGS. 1 and 2, the scanning device 220 scans the ionbeam 400 emitted in a direction of a Z-axis in a two dimensional planeconsisting of an X-axis and a Y-axis.

[0033] The scanning device 220 includes a disc 221, a disc-drivingmember 223 for driving the disc 221, a scanning arm 224, a Y-axisdriving member 225 for driving the disc 221 in a direction of theY-axis, a housing 226, a pipe 227 and a detecting device 228 fordetecting an ion beam. The disc 221 is rotated on a rotating axisthereof by the disc-driving member 223. A plurality of wafer holders 222are formed on peripheral portions of the disc 221, and the wafers W arerespectively received in each of the wafer holders 222.

[0034] The housing 226 is mounted at a free end of the scanning arm 224,and the disc-driving member 223 is installed in the housing 226. TheY-axis driving member 225 is fixed to a fixed end of the scanning arm224, and thus the scanning arm is moved in the direction of the Y-axis,that is, upwardly and downwardly, according to an operation of theY-axis driving member 225.

[0035] The pipe 227 is connected to an outer surface of the upperperipheral portion of the housing 226 to be extended outwardly. Thedetecting device 228, for example a spillover cup, is installed to aterminal end of the pipe 227.

[0036] The detecting device 228 detects a deviated ion beam that is outof the edge of the disc 221 to improve efficiency of the ion beam.

[0037] The ion beam 400 accelerated by the accelerator 300 is emitted insuch a manner that the ion beam 400 is irradiated on the wafer Wreceived in the wafer holder 222. A plurality of faraday cups 260 aremounted at a front of the wafer holder 222 and are spaced apart by apredetermined distance from one another and measure an electric currentof the ion beam.

[0038] An operation of the batch type ion implanter having theabove-mentioned construction will now be described.

[0039] The scanning arm 224 is rotated sufficiently so that the disc 221is positioned to be almost horizontal with the wafer transferring device230. Accordingly, an upper portion of the disc 221 is closely adjacentto the wafer-transferring device 230. Then, a plurality of the wafers Whaving been received in the wafer-transferring device 230 aretransferred into each of the wafer holders 222 by one sheet unit. Inother words, when one sheet of the wafer W is transferred into each ofthe wafer holders 222, the disc 221 is rotated at a predetermined angleso that a next wafer holder is positioned closely adjacent to the wafertransferring device 230 into which another sheet of the wafer W istransferred.

[0040] When all of the wafers W are loaded in the wafer holders 222, thescanning arm 224 is rotated in a reverse direction so that the disc 221is positioned to be almost vertical with the wafer-transferring device230. Accordingly, the wafer holders 222 are positioned adjacent to thefaraday cups 260, so that the ion beam 400 may be irradiated onto thewafer W. Subsequently, the ion beam 400 is irradiated onto the wafers Wwhile the disc 221 is rotated, and thus the ion beam 400 uniformly scansthe surfaces of the wafers W.

[0041] Possible causes of the particles and potential solutionscorresponding to each of the causes of the particles will now bedescribed.

[0042] Mechanical Particles

[0043] Vacuum Type Particles

[0044] When a lord lock chamber is locked and a vacuum state is providedtherein by dropping an inner pressure of the lord lock chamber, moistureis generated on a surface of a wafer that is inside the lord lockchamber due to a rapid temperature decrease which occurs in response tothe drastic decrease in pressure. Then, the moisture absorbs anddeposits particles, which generates vacuum type particles. As a solutionfor preventing the vacuum type particles, the pressure in the lord lockchamber is regulated to drop slowly enough that moisture is notgenerated on the wafer. Another solution is to purge the wafer with apurging gas, for example a nitrogen gas, before the lord lock is locked.

[0045] Abrasion Type Particles

[0046] Misalignment of opening portions of the ion implanter, forexample faraday cups positioned on a pathway of the ion beam, generatesparticles composed of Mo, Al and C, referred to as abrasion typeparticles. The abrasion type particles are low-energy particles and arenot deposited on the wafer but merely cover the wafer. A periodic checkof alignments of the ion implanter is required for preventing thegeneration of the abrasive type particles.

[0047] Preventive Maintenance Particles

[0048] A defect in preventive maintenance of unit parts of the ionimplanter reduces moisture contained in a small gap between the unitparts. At this time, particles such as H₂O₂ and oxide aluminum aregenerated, which are referred to as preventive maintenance particles. Animprovement in and a standardization of the preventive maintenance mayprevent the generation of preventive maintenance particles.

[0049] Electrical Particles

[0050] Arc Type Particles

[0051] Arc type particles are composed of Al, Fe, Ti, SUS and the likeand generate a long tail on a front surface of a wafer. The arc typeparticles are high-energy particles. In order to prevent the generationof arc type particles, it is suggested that secondary electrons berestrained from being generated or an electric bias be prevented frombeing applied to the front surface of the wafer.

[0052] Static Electricity Particles

[0053] Static electricity particles are activated particles, composed ofC (graphite), for example, due to negative charges. Static electricityparticles have strong electro-negativity but merely cover the wafer. Inorder to prevent the generation of static electricity particles, it issuggested that graphite particles be restrained from being generated andthe inside of a vacuum chamber be periodically cleaned out.

[0054] Sputtering Type Particles

[0055] Sputtering type particles are generated due to an impact of theion beam and are composed of C, Al, Fe, Ti, SUS and the like. Sputteringtype particles are mainly generated at an edge of the wafer. In order toprevent the generation of sputtering type particles, it is suggestedthat a stress per second, or a force per second, applied to a unit areaof the wafer be minimized by means of regulating an alignment andintensity of the ion beam.

[0056] The causes of the particles have been analyzed and significantattention has been devoted to the sputtering particles generated on asurface of the spillover cup since the spillover cup is a main sourcefor supplying metal sputtering particles.

[0057] The spillover cup is fixed at an edge of the disc 221 and iscontinuously subjected to an impact due to the ion beam during an ionimplanting process. Therefore, the surface of the spillover cup issputtered by a relatively continuous impact from the ion beam incomparison with the surface of the disc.

[0058]FIG. 3 illustrates a view explaining a change in a number ofsputtering particles generated on an edge portion of a wafer relative toa change in height of a spillover cup from a horizontal surface of thewafer.

[0059] Experimental results regarding an effect on the number ofsputtering particles generated as a result of changing the height of thespillover cup with respect to the height of the wafers received in thedisc are shown in FIG. 3. Referring to FIG. 3, the height of thespillover cup with respect to the surface of the wafer is directlyproportional to the number of sputtering particles generated. In otherwords, the higher the spillover cup is with respect to the surface ofthe wafer, the greater the number of sputtering particles generated is,and hence, the greater a degree of pollution on an edge portion of thewafer is due to the sputtering particles.

[0060] According to the conventional art, a silicon resin is coated on asurface of the spillover cup formed of aluminum in order to prevent thegeneration of sputtering particles. However, the silicon resin merelyprevents abrasion of the surface of the spillover cup but does notrestrain the generation of the sputtering particles.

[0061] When the spillover cup is positioned below the surface of thewafer, the degree of pollution of the wafer due to the particles may befurther decreased. However, using this configuration, secondaryelectrons are difficult to control since the wafer is positioned a largedistance from the faraday cup, which is mounted at a front of the ionimplanter. Therefore, the spillover cup is preferably positioned abovethe surface of the wafer.

[0062]FIG. 4 illustrates a table showing a lifetime of the spillover cup228 with respect to a size of a generating current used for generatingthe ion beam. FIG. 5 illustrates a graph showing the relationshipbetween a corrosion rate of the spillover cup (in mA-hr) and the size ofthe generating current (in micrometers).

[0063] Increasing the generating current for generating the ion beamincreases a power of the ion beam. Therefore, as shown in FIGS. 4 and 5,the higher the generating current for generating the ion beam, thegreater the number of particles generated due to the increased power ofthe ion beam. For example, when an ion beam is emitted to a targetregion of a wafer, an impact force of an ion beam generated by agenerating current of approximately 1 mA to 20 mA is stronger than theimpact force of an ion beam generated by a generating current ofapproximately 10 μA to 1 mA. Consequently, the stronger the impactforce, the higher the corrosion rate and the greater the number ofparticles generated.

[0064] Accordingly, in an ion implanter using a high voltage current,pollution of a wafer due to sputtering particles has an adverse effecton dies adjacent to the wafer, and thus the electrical characteristicsof the dies are significantly changed. The change of the electricalcharacteristics of the dies causes electrical defects in a semiconductordevice, and consequently the product yield is decreased.

[0065]FIG. 6 illustrates a view showing a scattering process ofsputtering particles on a flat surface of a conventional spillover cup.

[0066] Referring to FIG. 6, a surface of the spillover cup 228 is flat.Therefore, when the surface of the spillover cup 228 is positionedhigher than a surface of the wafer W due to misalignment, the degree ofpollution of the wafer W due to sputtering particles becomes high.

[0067] In other words, since the surface of the spillover cup 228 ispositioned normal to a direction of the ion beam, a scattering angle ofthe sputtering particles is so large that the particles fall on theadjacent wafer when the ion beam collides against the surface of thewafer.

[0068] The spillover cup 228 can hardly be aligned exactly with thesurface of the wafer W since the spillover cup 228 is installed at theterminal end of the pipe 227 fixed to the housing 226, as shown in FIG.2. Even if the spillover cup is originally in perfect alignment with thesurface of the wafer, over time, stresses due to vibration or heatexpansion of the disc while the disc is rotated usually cause thespillover cup 228 to become misaligned and positioned higher than thesurface of the wafer.

[0069] Furthermore, a surface of the spillover cup is worn away overtime, necessitating periodic replacement of the worn-away spillover cupwith a new one. Again, the new spillover cup can hardly be alignedexactly with the surface of the wafer.

[0070] Accordingly, in another embodiment of the present invention, animproved spillover cup is provided to solve the problem described above.

[0071]FIG. 7 illustrates a view showing a scattering process ofsputtering particles on an inclined surface of the spillover cup of abatch type ion implanter according to an embodiment of the presentinvention.

[0072] Referring to FIG. 7, the spillover cup 229 has an inclinedsurface and is preferably comprised of aluminum. The surface of thespillover cup may be coated with silicon resin. Additionally, thespillover cup 229 may be comprised of vitreous graphite.

[0073] A gradient of the inclined surface of the spillover cup 229 is inan angle range of approximately 10 degrees to 30 degrees. The gradientprevents the ion beam from perpendicularly colliding against the surfaceof the spillover cup, and hence collision energy of the ion beam isdispersed. Furthermore, the scattering angle of the particles is smallenough that the particles are not able to cross over an edge of the disc221. Hence, the particles generated from the surface of the spillovercup disappear after colliding against a side surface of the disc 221. Asa result, the number of particles falling on the wafer received in thedisc 221 may be significantly reduced.

[0074] More particularly, the gradient of the surface of the spillovercup sufficiently reduces a rebounding force of the ion beam below areference force so that the sputtering particles disappear aftercolliding against the edge of the disc 221.

[0075] When the gradient is less than an angle of 10 degrees, thesputtering particles are scattered over the wafer W since a slope of thesurface of the spillover cup is slight, and pollution of the edgeportion of the wafer W cannot be significantly improved.

[0076] When the gradient is more than an angle of 30 degrees, theparticles are not scattered over the wafer W. However, since thesecondary electrons generated by the collision of the ion beam cannotreach the faraday cup 260 mounted at a front of the disc 221, thefaraday cup cannot be used for controlling the secondary electrons.

[0077] In other words, when the spillover cup 229 is far away from thefaraday cup 260, a magnetic field is difficult to control, and thus, thesecondary electrons are difficult to control.

[0078] According to a preferred embodiment of the present invention, thegradient of the surface of the spillover cup 229 is formed with an anglein a range of approximately 10 degrees to 30 degrees, thereby preventingthe sputtering particles from being scattered on the wafer W while thesecondary electrons are effectively controlled by forming a proper spacebetween the spillover cup and the faraday cup.

[0079]FIG. 8 illustrates a sectional view showing a sampling beam cup ofa single type ion implanter according to another embodiment of thepresent invention.

[0080] The single type ion implanter can hold only one wafer W in thewafer holder 500, contrary to the batch type ion implanter, and scansupward and downward, or leftward and rightward, in the scanning region.Similar to the batch type ion implanter, in the single type ionimplanter, a sampling beam cup 600 is also mounted at a positionadjacent to the wafer holder 500 for sampling the ion beam emitted onthe wafer W.

[0081] Referring to FIG. 8, the sampling beam cup 600 has an inclinedsurface that is formed in a similar way in which the surface of thespillover cup of the batch type ion implanter is formed. Accordingly,the sputtering particles generated from the surface of the sampling beamcup 600 are prevented from being scattered on the wafer W.

[0082] According to preferred embodiments of the present invention, ayield of products utilizing semiconductor devices may be greatlyimproved by reducing the number of sputtering particles generated in theion implanter in fabricating the semiconductor devices having widths of0.18 μm or 0.16 μm. Even though the fixed spillover cup is raised abovea spin disc due to vibration and heat expansion during the ionimplanting process, the sputtering particles may not pollute a surfaceof the wafer since the surface of the spillover cup is inclined.

[0083] Preferred embodiment of the present invention have been disclosedherein and, although specific terms are employed, they are used and areto be interpreted in a generic and descriptive sense only and not forpurpose of limitation. Accordingly, it will be understood by those ofordinary skill in the art that various changes in form and details maybe made without departing from the spirit and scope of the presentinvention as set forth in the following claims.

What is claimed is:
 1. An ion implanter comprising: means for scanningan ion beam on a wafer, the scanning means moving the wafer in a regionwhere the ion beam is irradiated, the wafer being mounted on thescanning means; and means for detecting an ion beam that is overlyscanned out of the ion beam scanning means, the detecting means beingfixedly mounted adjacent to the ion beam scanning means, wherein thedetecting means has an inclined surface so that a portion of thedetecting means adjacent to the scanning means is positioned below asurface of the wafer that is disposed on the scanning means.
 2. An ionimplanter as claimed in claim 1, wherein a gradient of the inclinedsurface of the detecting means is in an angle range of approximately 10degrees to 30 degrees.
 3. An ion implanter as claimed in claim 1,wherein the detecting means is an aluminum plate having a surface coatedwith a silicon resin.
 4. An ion implanter as claimed in claim 1, whereinthe detecting means is comprised of vitreous graphite.
 5. An ionimplanter as claimed in claim 1, wherein the scanning means has a discshape for mounting a plurality of wafers thereon.
 6. An ion implanter asclaimed in claim 1, wherein the scanning means moves the wafer in aregion where the ion beam is irradiated.
 7. An ion implanter as claimedin claim 1, wherein the ion implanter is a single type ion implanter. 8.An ion implanter as claimed in claim 7, wherein the scanning meansincludes a wafer holder.
 9. An ion implanter as claimed in claim 7,wherein the detecting means includes a spillover cup.
 10. An ionimplanter as claimed in claim 9, wherein the spillover cup is comprisedof aluminum.
 11. An ion implanter as claimed in claim 9, wherein thespillover cup has a surface coated with a silicon resin.
 12. An ionimplanter as claimed in claim 9, wherein the spillover cup is comprisedof vitreous graphite.
 13. An ion implanter as claimed in claim 9,wherein the spillover cup has an inclined surface.
 14. An ion implanteras claimed in claim 13, wherein a gradient of the inclined surface ofthe spillover cup is in an angle range of approximately 10 degrees to 30degrees.
 15. An ion implanter as claimed in claim 7, wherein thedetecting means includes a sampling beam cup.
 16. An ion implanter asclaimed in claim 15, wherein the sampling beam cup has an inclinedsurface.
 17. An ion implanter as claimed in claim 16, wherein a gradientof the inclined surface of the sampling beam cup is in an angle range ofapproximately 10 degrees to 30 degrees.
 18. An ion implanter as claimedin claim 1, wherein the ion implanter is a batch type ion implanter. 19.An ion implanter as claimed in claim 18, wherein the scanning meansincludes a rotary disc.
 20. An ion implanter as claimed in claim 18,wherein the detecting means includes a spillover cup.
 21. An ionimplanter as claimed in claim 20, wherein the spillover cup is comprisedof aluminum.
 22. An ion implanter as claimed in claim 20, wherein thespillover cup has a surface coated with a silicon resin.
 23. An ionimplanter as claimed in claim 20, wherein the spillover cup is comprisedof vitreous graphite.
 24. An ion implanter as claimed in claim 20,wherein the spillover cup has an inclined surface.
 25. An ion implanteras claimed in claim 24, wherein a gradient of the inclined surface ofthe spillover cup is in an angle range of approximately 10 degrees to 30degrees.
 26. An ion implanter as claimed in claim 18, wherein thedetecting means includes a sampling beam cup.
 27. An ion implanter asclaimed in claim 26, wherein the sampling beam cup has an inclinedsurface.
 28. An ion implanter as claimed in claim 27, wherein a gradientof the inclined surface of the sampling beam cup is in an angle range ofapproximately 10 degrees to 30 degrees.
 29. An ion implanter as claimedin claim 1, wherein the scanning means includes a rotary disc applied ina batch type ion implanter.
 30. An ion implanter as claimed in claim 1,wherein the scanning means includes a wafer holder applied in a singletype ion implanter.
 31. An ion implanter as claimed in claim 1, whereinthe detecting means includes a spillover cup.
 32. An ion implanter asclaimed in claim 31, wherein the spillover cup has an inclined surface.33. An ion implanter as claimed in claim 32, wherein a gradient of theinclined surface of the spillover cup is in an angle range ofapproximately 10 degrees to 30 degrees.
 34. An ion implanter as claimedin claim 31, wherein the spillover cup is comprised of aluminum.
 35. Anion implanter as claimed in claim 34, wherein the spillover cup has asurface coated with a silicon resin.
 36. An ion implanter as claimed inclaim 31, wherein the spillover cup is comprised of vitreous graphite.37. An ion implanter as claimed in claim 1 wherein the detecting meansincludes a sampling beam cup.
 38. An ion implanter as claimed in claim37, wherein the sampling beam cup has an inclined surface.
 39. An ionimplanter as claimed in claim 38, wherein a gradient of the inclinedsurface of the sampling beam cup is in an angle range of approximately10 degrees to 30 degrees.